1. Field of the Invention
The present invention relates to locomotive braking systems and, more particularly, a powered handbrake integrated into a locomotive braking system.
2. Description of the Related Art
Locomotives generally have both a pneumatic brake system that is used when the locomotive is powered and operating, and a hand brake that is used when parking the locomotive. An application of the hand brake prevents a locomotive from rolling away if the air pressure in the brake cylinder leaks away, such as when the locomotive is parked for a long period of time. Because modern locomotives can weigh in excess of 400,000 pounds, a manually operated hand brake must generate a significant brake force to hold a locomotive on a grade. As a result, a manual application of a hand brake often requires substantial effort and achieving sufficient brake force is dependent on the strength and skill of the operator. In addition, a locomotive hand brake is located on outside the locomotive cab and accessed via the catwalk that extends along the locomotive. Operation of the hand brake can thus pose a safety risk, particularly during inclement weather.
In order to address these issues, powered hand brakes have been introduced. For example, U.S. Pat. No. 6,427,811 discloses a hand brake that requires a high-powered electric motor in combination with a complex and expensive gear train to develop the required output force. Systems such as this also require complex feedback methods to sense the output load and shut down the motor when the required force has been achieved. A failure of the feedback method can result in blown fuses, physical damage to the components, or insufficient brake force. As a result, there is a need for a powered handbrake that is operable from the cab of the locomotive and does not require a complex or fault prone design.